This invention is directed to telephones and more particularly, to rotary dial or push-button (i.e. Touch Tone) types which complete a call by making desired connections at a telephone company central office. For purposes of illustration, a push-button telephone will be referred to. However, the comments relate as well to a rotary (dial) type. Therefore, reference made to a Touch Tone telephone are not to be considered as a limitation of the present invention. With regard to the push-button or Touch Tone type, by selectively pressing and releasing a numbered sequence of plungers on a numerical face plate on a telephone, a plurality of different tones or frequencies are respectively generated on the subscriber's line, the number called depending upon the tones created by the various plungers depressed and released. The electrical tone or frequencies thus generated are transmitted to the central office where they control the movement of an electro-mechanical device called a selector through which the subscriber's line is connected to other selective mechanisms. Each successive digit formed by the plungers produces another series of such tones which advance the call one step toward completion until the final operation occurs whereby connection is made to the called telephone.
The use of Touch Tone push-button telephones is being gradually extended in this country and in all parts of the world. Additionally, the Touch Tone telephones are so preferred that toll calls can be made directly by the caller or subscriber through new central station equipment. However, the subscriber may not authorize the caller to make such toll or local calls and thus he is charged for calls he knows nothing about.
Further, it is desirable to utilize the telephone to control incoming calls so that they can be switched to other necessary circuits if desired.
What is more, the telephone user may frequently receive an incoming call at an inconvenient time. That is, and by way of a first example, the user may desire to communicate with a caller at a more suitable (i.e. comfortable) place, where a telephone accessory (i.e. extension) circuit is located. By way of a second example, an incoming telephone call may find the recipient temporarily occupied with a task, such as cooking, or the like. In both of the aforementioned cases, it would be desirable that the user have access to an inexpensive and compact device by which to place his telephone in a hold condition so as to permit him to return the telephone handset to its associated cradle without disconnecting an existing call. In this way the user can have the time necessary to either complete his task or move to the more suitable location of a telephone extension before resuming his conversation. Moreover, and in the event that the user wishes to complete the conversation from a remote telephone extension, it would be advantageous for the user to first be able to return the original telephone handset to its cradle without later seeking the assistance of an additional person.